High Molecular Weight Kininogen
Plasma high molecular weight kininogen (HK) is a 120 kD glycoprotein encoded by a single gene (Kitamura et al., J. Bio. Chem. 1985; 260:8610–8617). The first 9 exons code for the heavy chain domains 1–3, and exon 10 codes for bradykinin (BK) domain 4 and the light chain, domains 5 and 6. Mediation of the biological effects of HK requires prior cell binding. Domain 3 (D3) inhibits thrombin action on platelets (Puri et al., Blood 1991; 77:500–507) as well as cell binding to platelets (Kunapuli etal., J. Bio. Chem. 1996; 271:11228–11234), endothelial cells (Herweld et al., J. Bio. Chem. 1995; 270:14634–14642) and neutrophils (Wachtfogel et al., J. Bio. Chem. 1994; 269:19307–19312; Khan et al., Am. J. Physiol. 1998; 275:H145–H150). Following the cleavage of BK from HK, the heavy and light chains resulting from the elimination of BK remain linked by a disulfide bond between cysteine residues at positions 10 and 656. The resulting active cofactor, HKa, undergoes major conformational changes detected by electron microscopy (Weisel et al., J. Bio. Chem. 1994; 269:10100–10106) and circular dichroism (Villanueva et al., Biochem. Biophys. Res. Commun. 1989; 158:72–79), and acquires the ability to bind to anionic surfaces (Scott et al., J. Clin. Invest. 1984; 73:954–962).
The HK light chain consists of the following sequence of HK amino acids 372–626 (SEQ ID NO:1):                S S R I G E I K E E T T V S P P H T S M A P A Q D E E R D S G K E Q G H T R R H D W G H E K Q R K H N L G H G H K H E R D Q G H G H Q R G H G L G H G H E Q Q H G L G H G H K F K L D D D L E H Q G G H V L D HG H K H K H G H G H G K H K N K G K K N G K H N G W K T E H L A S S S E D S T T P S A Q T Q E K T E G P T P I P S L A K P G V T V T F S D F Q D S D L I A T M M P P I S P A P I Q S D D D W I P D I Q T D P N G L S F N P I S D F P D T T S P K C P G R P W K S V S E I N P T T Q M K E S Y Y F D L T D G L S (SEQ ID NO:1).        
The HK light chain amino acids (Ser)372 to Thr(383) form the C-terminal portion of HK domain 4 remaining after bradykinin liberation. HK amino acids Val(384) to Lys(502) form the HK domain 5 (D5). HK amino acids Thr(503) to Ser(626) form the HK domain 6 (D6). Within D5, critical amino acids His(441)-His(457) in a histidine-glycine-rich region are responsible for binding to an artificial negatively-charged surface (DeLa Cadena et al., Prot. Sci. 1992; 1:151–160). Thus, HKa formation results in the exposure of D5. Using deletion mutagenesis, a second subdomain has been defined: a histidine-glycine-lysine-rich region (residues His(475)—Lys(502)) which also supports binding to an anionic surface (Kunapuli et al., J. Biol. Chem. 1993; 268:2486–2492). Hasan et al. (Hasan et al., J. Biol. Chem. 1995; 270:19256–19261) have mapped the endothelial cell binding domain on D5 to the histidine-glycine-lysine-rich region, specifically residues His(471)-Gly(496), which could represent a second region for cell interaction. Khan et al. (Kahn et al., Am. J. Physiol. 1998; 275:H15-H150) have localized neutrophil binding to the histidine-glycine region. The binding of D5 to cells appears to be responsible for the “anti-adhesive” action of HKa on neutrophils and platelets (Gustafson et al., J. Cell. Biol. 1989; 109:377–387). Asakura et al. (Asakura et al., J. Cell. Biol. 1992; 116:465–476) showed that HKa inhibits the adhesion and spreading of human osteosarcoma cells on vitronectin-coated polystyrene plates, and the spread of bovine aortic endothelial cells on vitronectin. The C-terminus of the light chain of HK D6, spanning Ser(565) to Lys(595), is required for the binding of prekallikrein (Tait et al., J. Biol, Chem. 1987; 262:1405–1411).
Monoclonal Antibodies Against HK
Monoclonal antibody C11C1 of U.S. Pat. No. 4,908,431 to Colman etal is produced by hybridoma ATCC HB 8964 and recognizes the HK light chain. The antibody inhibits the coagulant activity of HK (Schmaier et al., J. Biol. Chem. 1987; 262:1405–1411), a property of the light chain, but not the ability of HK to inhibit the cysteine protease, calpain (Bradford et al., Biochem. J. 1990; 270:83–90), a property of the heavy chain. Further investigation indicated that MAb ClI C1 inhibits binding of 125I-HK to the anionic surface of kaolin (DeLa Cadena et al, Prot. Sci. 1992; 1:151–160), and inhibits binding of kininogen to neutrophils (Wachffogel et al., J. Bio. Chem. 1994; 269:19307–19312). MAb C11C1 is described in U.S. Pat. No. 4,908,431 as being useful for measuring kininogen levels in plasma and other specimens of interest. The antibody is also described as being useful in removing kininogen from blood or other body fluids, for the treatment of diseases characterized by elevated kininogen levels. No other therapeutic uses for MAb C11C1 are disclosed in Pat. 4,908,431.
Reddigari and Kaplan, Blood 74:695–702 (1989) describe a monoclonal antibody 115–21 which is specific for the prekallikrein binding site on HK domain 6. MAb 115–21 is disclosed as being possibly useful in delineating the role of HK and prekallikrein in contact activation and kinin-related human pathology.
Angiogenesis
Angiogenesis is the process in which new blood vessels grow into an area which lacks a sufficient blood supply. Angiogenesis commences with the erosion of the basement membrane surrounding endothelial cells and pericytes forming capillary blood vessels. Erosion of the basement membrane is triggered by enzymes released by endothelial cells and leukocytes. The endothelial cells then migrate through the eroded basement membrane when induced by angiogenic stimulants. The migrating cells form a “sprout” off the parent blood vessel. The migrating endothelial cells proliferate, and the sprouts merge to form capillary loops, thus forming a new blood vessel.
Angiogenesis can occur under certain normal conditions in mammals such as in wound healing, in fetal and embryonic development, and in the formation of the corpus luteum, endometrium and placenta. Angiogenesis also occurs in certain disease states such as in tumor formation and expansion, or in the retina of patients with certain ocular disorders. Angiogenesis can also occur in a rheumatoid joint, hastening joint destruction by allowing an influx of leukocytes with subsequent release of inflammatory mediators.
The evidence for the role of angiogenesis in tumor growth was extensively reviewed and presented by O'Reilly and Folkman in U.S. Pat. No. 5,639,725, the entire disclosure of which is incorporated herein by reference. It is now generally accepted that the growth of tumors is critically dependent upon angiogenesis. It has been proposed to inhibit angiogenesis with peptides (e.g., angiostatin and endostatin), recombinant proteins, and monoclonal antibodies directed to angiogenic proteins such as basic fibroblast growth factor (FGF-2) or vascular endothelial growth factor (VEGF) or their cellular receptors.
Additional therapeutic agents are desired for inhibition of angiogenesis. The inhibition of angiogenesis with antibodies against HK has not been proposed prior to the present invention.